1. Field of the Invention
The present invention relates to a catalyst and a process of using the same for removing toxic gaseous hydrides from a gas stream.
2. Description of the Background
Various methods are known for the removal of gaseous hydrides from gas mixtures. Such gaseous hydrides are silane, disilane, trisilane, germane, arsine, phosphine, hydrogen sulfide, hydrogen selenide and diborane. For example, methods involving combustion or incineration, absorption by gas-liquid reaction or dry-type chemisorption are known.
Activated carbons have been used for toxic gas removal in several instances. However, plain-activated carbons have only adsorptive capabilities against hydrides, which may be released by desorption. For example, the use of impregnated carbons for arsine removal has been reported in U.S. Pat. No. 2,511,289. This technique has been specifically used in semiconductor applications. More recently, other studies have been reported for arsine and phosphine removal.
Certain metal oxide catalysts are known to react irreversibly with hydrides and their use for removing arsine and hydrogen sulfide has been noted in U.S. Pat. No. 4,593,148. In this patent, the use of CuO and ZnO is described. Unfortunately, cupric oxide, in conjunction with other oxides like zinc oxide, only absorbs a finite amount of hydride.
Thus, a need continues to exist for metal oxide catalysts, particularly cupric oxide catalysts, having an improved ability to absorb gaseous hydrides, for example, based upon the absorbed amount per volume of bed. With such an improvement, it would also be possible to extend the lifetime of catalysts made from such materials. Improved safety and a reduced cost of production would also thereby be attained.